In the past, there have been various types of high impact hose couplings used in sandblasting and the like. These couplings consisted of two coupling halves usually constructed of some type of metal. All hose couplings had some type of locking mechanism to lock the coupling halves together and, in some instances, a second locking means to prevent the coupling halves from rotating out of a locked relationship, where the primary locking mechanism consisted of rotating the coupling halves into a locking relationship. For example, U.S. Pat. Nos. 2,132,506 and 3,498,641 show hose couplings with a primary locking mechanism for the coupling and a spring wire locking mechanism to prevent the coupling halves from rotating out of their locked position. Another prior art patent, U.S. Pat. No. 1,914,368, shows a primary locking mechanism and a second method of preventing rotation of coupling halves out of their locked relationship.
To ensure that there was not any leakage at the point of union of the coupling halves, the prior art disclosed various gaskets and gasket configurations disposed at the union. Prior art gasket configurations are represented in U.S. Pat. Nos. 2,816,779, 3,758,137 and 3,831,984.
The prior art relating to hose couplings has additionally been concerned with methods of attaching the hose to a respective coupling half. The connections for the hose have been represented in many cases by frusto-conical coupling sections, which receive the hose on the outside of that section, as is shown in U.S. Pat. Nos. 1,914,368, 3,498,641, 3,758,137 and 3,831,984. There are other methods of attaching a hose to a coupling half, such as that requiring a special end piece to mate with the internal threading of the hose coupling as represented by U.S. Pat. No. 2,816,779.
A major problem in sandblasting in the past has been the build-up of static electricity in the hose due to the rapid flow of sand in the hose and in the coupling. The hose had to be grounded to prevent shock or arcing at the couplings. As static electricity built up, the flow of static electricity would be from the nozzle to the adjacent hose section, to the coupling, to the next hose section and so on until contact with ground was established. The ground could be established at the sand source or at intermediate places along the hose. If the hose was not grounded, the static electricity could build up in the hose to a point where there was electric shock and/or arcing at the coupling causing personal injury or damage.
In situations where non-metallic couplings were used, the concern over the static electricity flow became more acute. When there were metallic couplings there could be a continuous flow of the static electricity to ground. However, when there were non-metallic couplings, there could not be a continuous flow through the coupling itself, and the gasket material would serve as an insulating barrier between the coupling halves. The result would be a static electric build-up in the separate hose sections that could cause damage to the hose.
The use of a non-metallic coupling was considered highly desirable in the past because there was never a danger of arcing at the coupling when in close proximity to a metallic object. This feature was attractive when sandblasting operations were being conducted in an area where there were flammable gases present. However, there still existed the problem of how to dissipate the static electric build-up in the hose sections when non-metallic couplings were used due to the insulating features of the coupling itself and the gasket.
The present invention overcomes the problems inherent in the use of the non-metallic couplings of the past.
An object of the invention is to provide an improved non-metallic hose coupling.
Another object of the invention is to provide an improved hose coupling having two locking mechanisms to maintain a locking relationship between two coupling halves.
A further object of the invention is to provide an improved hose coupling having a helical restriction means to attach the hose to a coupling half.
A still further object of the invention is to provide an improved hose coupling with a static electricity dissipating gasket to allow static electricity dissipation from the hose nozzle throughout the hose and couplings to a ground at a sand source.